Marker aided introgression of opaque 2 (o2) allele improving lysine and tryptophan in maize (Zea mays L.)

Bharathi Pukalenthy; Dhasarathan Manickam; Karthikeyan Adhimoolam; Sandesh Goragundi Mahesh; Nagalakshmi Ramanathan; Sarankumar Chandran; Vellaikumar Sampathrajan; Ravikesavan Rajasekaran; Kavithapushpam Arunachalam; Kalaiselvi Senthil; Vignesh Muthusamy; Firoz Hossain; Senthil Natesan

doi:10.1007/s12298-020-00857-4

Marker aided introgression of opaque 2 (o2) allele improving lysine and tryptophan in maize (Zea mays L.)

Physiol Mol Biol Plants. 2020 Sep;26(9):1925-1930. doi: 10.1007/s12298-020-00857-4. Epub 2020 Aug 25.

Affiliations

¹ Department of Plant Breeding and Genetics, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai, Tamil Nadu India.
² Department of Biotechnology, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai, Tamil Nadu India.
³ Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu India.
⁴ Department of Plant Molecular Biology and Bioinformatics, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu India.
⁵ Department of Millets, Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu India.
⁶ Department of Soil Science and Agricultural Chemistry, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Killikulam, Tamil Nadu India.
⁷ Department of Biochemistry, Biotechnology and Bioinformatics, Avinashilingam Institute for Home Science and Higher Education for Women, Coimbatore, Tamil Nadu India.
⁸ Division of Genetics, Indian Agricultural Research Institute, New Delhi, India.

Abstract

Maize is the predominant food source for the world population, but lack of lysine and tryptophan in maize endosperm cannot fulfill the nutritional requirements of humans. Hence, the improvement of lysine and tryptophan content is the ultimate goal of maize biofortification programs. In the present study, the marker-assisted backcross (MABC) breeding strategy was used to enhance the lysine and tryptophan content of the elite maize inbred line UMI1230 by introgressing opaque 2 (o2) gene from the VQL1. During the transfer of the gene into UMI1230, SSR marker umc1066 tightly associated with o2 used for foreground selection. Background recovery was estimated using 168 SSR markers. Phenotype screening for morphological traits was adopted to choose plants parallel to UMI1230. As a result, four BC₂F₃ improved lines (DBT5-1-14/25-5/25-8/25-8/25, DBT5-1-14/25-5/25-8/25-7/25, DBT5-1-14/25-5/25-8/25-10/25 and DBT5-1-14/25-5/25-8/25-12/25) with o2 were developed. The improved line's background genome recovery varied between 90.60 and 94.80%. Also, the improved lines had better agronomic performance along with increased lysine (0.311-0.331%) and tryptophan (0.040-0.048%) contents. In summary, the MABC breeding strategy has successfully improved the levels of lysine and tryptophan in UMI1230 without affecting agronomic performance. The improved line's hold great potential as donors in biofortification programs in maize.

Keywords: Biofortification; Maize; Marker-assisted backcrossing; opaque 2.